Create README.md

docs/examples/library-experimental-features/README.md

+# Use go-ipfs as a library and enable experimental features
+
+Before moving on to this tutorial, you must read first the initial [`go-ipfs` as a library tutorial](../go-ipfs-as-a-library/README.md)
+as it gives insights on how to create a repository, the daemon and add a file.
+
+There is only one thing that differs from this example and the first tutorial, which is the function [`createTempRepo`](../go-ipfs-as-a-library/main.go#L49):
+
+```go
+func createTempRepo(ctx context.Context) (string, error) {
+	repoPath, err := ioutil.TempDir("", "ipfs-shell")
+	if err != nil {
+		return "", fmt.Errorf("failed to get temp dir: %s", err)
+	}
+
+	// Create a config with default options and a 2048 bit key
+	cfg, err := config.Init(ioutil.Discard, 2048)
+	if err != nil {
+		return "", err
+	}
+
+	// Create the repo with the config
+	err = fsrepo.Init(repoPath, cfg)
+	if err != nil {
+		return "", fmt.Errorf("failed to init ephemeral node: %s", err)
+	}
+
+	return repoPath, nil
+}
+```
+
+When creating the repository, you can define custom settings on the repository, such as enabling [experimental
+features](../../experimental-features.md) or customizing the gateway endpoint.
+
+To do such things, you should modify the variable `cfg`. For example, to enable the sharding experiment, you would modify the function to:
+
+```go
+func createTempRepo(ctx context.Context) (string, error) {
+	repoPath, err := ioutil.TempDir("", "ipfs-shell")
+	if err != nil {
+		return "", fmt.Errorf("failed to get temp dir: %s", err)
+	}
+
+	// Create a config with default options and a 2048 bit key
+	cfg, err := config.Init(ioutil.Discard, 2048)
+	if err != nil {
+		return "", err
+	}
+	
+	// Customize configuration
+	cfg.Experimental.ShardingEnabled = true
+
+	// Create the repo with the config
+	err = fsrepo.Init(repoPath, cfg)
+	if err != nil {
+		return "", fmt.Errorf("failed to init ephemeral node: %s", err)
+	}
+
+	return repoPath, nil
+}
+```
+
+There are many other options that you can find through the [documentation](https://godoc.org/github.com/ipfs/go-ipfs-config#Config).